Metrics-PerceivedComplexity.md

Pattern: Perceived complexity is too high

Issue: -

Description

This rule tries to produce a complexity score that's a measure of the complexity the reader experiences when looking at a method. For that reason it considers when nodes as something that doesn't add as much complexity as an if or a &&. Except if it's one of those special case/when constructs where there's no expression after case. Then the rule treats it as an if/elsif/elsif... and lets all the when nodes count. This rule considers else nodes as adding complexity.

Examples

def my_method                   # 1
  if cond                       # 1
    case var                    # 2 (0.8 + 4 * 0.2, rounded)
    when 1 then func_one
    when 2 then func_two
    when 3 then func_three
    when 4..10 then func_other
    end
  else                          # 1
    do_something until a && b   # 2
  end                           # ===
end                             # 7 complexity points

Default configuration

Attribute	Value
Max	7

Further Reading

• RuboCop - Metrics/PerceivedComplexity